Welding rod coating



Patented Feb. 18,1936

v UNITED STATES PATENT OFFICE WELDING ROD COATING- Paul C. Lemmerman, East Cleveland, Ohio, as-

signor to The Grassclli Chemical Company. Cleveland, Ohio, a corporation of Delaware Application December 19,1933, Serial No. 703,158 12 Claims. (01. ale-8i FeOa'SiOz where a: is usually one or more. By'

reason of the wide'vari'ation of their'composition these slags have not been found suitable for,

commercial use. The melting points of different slags vary widely,'and are usually too high. Moreover, the quantity of sulfur, phosphorous, and other impurities in these slags is rather large. with the result that when they are used, the welded joint contains phosphorous, sulfur, etc.

In order to obtain even fair results the art has been forced to abandon these FeO-xSiOz containing materials and to use talc, titanium compounds, mechanical mixtures of iron oxides and silica, etc.

The use of mechanical mixtures of iron oxides and silica proved fairly satisfactory, as sulfur, phosphorous, and other impurities need not be present. However, 'such mixtures have rather high melting points, anditis very diflicult to obtain uniformity among different batches. Moresilica mixture are not maintained long enough over, the iron oxides, F8203 or F8304, must be reduced before a fused material can be obtained. Such a reduction uses up the organic reducing agents and'the ferromanganese, usually provided in the welding rod coating for other purposes. Another difliculty which has been experienced is that under ordinary welding conditions the high temperatures required to fuse the iron oxidetend to react with the silicateibinder usually usedin welding rod coatings. Also, since under ordinary welding conditions the required high temperatures are not 'long maintained, the gases formed by their decomposition may not be entirely removed from the weld metal and from the slag. I

.I have found that a compound of the type FeO-xCaOySiOz is very desirable as a slag forming ingredient, and at the same time acts as an arc stabilizer.

My novel slag forming materials are manu- 10 factured products of uniform composition and low, definite melting point, and are relatively free from impurities such as a sulfur, phosphorous, etc.

The melting points of my preferred materials 15 are lower than that of any composition of the type FeO-xSiOz. Due to their low melting points my materials remain very fluid until the weld metal solidifies. So, the slag solidifies on the surface of the weld metal instead of being 00- 20 cluded therein. It is very brittle and is easily rewhich has a melting point of about 1110 C.

For purposes of illustration I shall outline a process for the manufacture of this compound.

Iintimately mixed one mol of iron oxide, onehalf mol of lime, one and one-fourth mols of silica, and carbon. The mixture was turned into a graphite crucible and the crucible placed in an induction type electric furnace. The mixture was then fused at about 1540 C.

In order more clearly to understand the limits 45 I of my invention reference should be hadto the accompanying, diagrams. I

As seen in Figure 1, starting, with a composition A (FeO- ASiOz) and adding .lime, the melting point drops to about 1120 C. at the point B which represents a material of approximately the composition FeO /5CaO-%SiOz. With a further addition of lime the melting point increases to about 1220" C. at the point D which corresponds to a material of approximately the composition FeOc'ao-siOz. With a still further addition of lime the melting point increases to slightly over 1300 C. at point E which corresponds to a material of approximately the composition FeO- lfiCaOSiOz.

This composition E represents about my upper limit on CaO. In'general, for each mol of Fe() I may use no more than about 1 6 mols of 02.0, and I prefer to use no more than about 1 mol of 09.0. I prefer to use at least some CaO because of its effect as an arc stabilizer, and because of its effect of decreasing the melting point of the compound.

The eflect of varying the CaO in the formula FeO-zCaO-z SiOz has been seen. In Figure 2 is' illustrated the effect of varying the $102. The diagram of Figure 2 is for the system FeO- /2CaO- n mols S102. From the behavior of this typical ratio of FeO to CaO with various amounts of S102, I am able to set approximate limits on the, S10: variation.

In Figure 2 the point A represents a compound FeO-tCaO V4810: which has a melting point of about 1190 C. On addition ofsilica the melting point drops until at point B a melting point of about 1120 C. is reached. The point B represents approximately the composition.

FeO- K-CnOSiOz.

0n addition of more 810: the melting points drop slightly until point C is reached, about 1110 C. The point C represents approximately the composition FeO- ACaO-1V Si0z- A further addition of silica raises the melting point slowly until at point D a melting point of about 1130 C. is reached. The point D represents the composition FeO- /gcao-l bsioz. A further increase of SiO: rapidly raises the melting point until at point E a melting point of about 1300 C. is reached. The point E represents approximately the composition FeO ACaO-HSiOa. In general, I may use for each mol of FeO, between about V4, and 1% mols of S102. I prefer to use betwee from about 1 to 1 ,5 mols of S102.

The melting point of my preferred compounds is in no case substantially above 1300 .C. The formulae composition of my iron calcium silicates, above disclosed, may be represented as:

FeO-xCaO-uSiOz where :2: is less than about 1 and z/ is between about and 1%.

While I have discussed my compounds with reference to calcium, I do not intend to be limited thereto. Instead of calcium I may use barium in the heretofore described compounds. The type formula of mynovel welding rod coating compounds may be represented as follows:

lEeOzrMeO-IISiO:

where Me represents calcium or barium, and a: and 1! represent the number of mols of MeO and SiOz respectively.

In electric welding the welding rod should be provided with a suitable coating. Of course, the coating material may be put in the center of the rod as a core, etc., and when I refer to a coating herein I mean to include such equivalent manners of association.

An emcient coating should contain: an organic reducing material, such as a cellulosic material,

which burns in the arc to form a gaseous envelope that keeps atmospheric oxygen and nimn from the molten metal; feese which acts to deoxidize and increase the fluidity of the molten metal and to prevent the occlusion of FeO therein; iron calcium silicates. according to my invention, which function as heretofore disclosed; and a binder such as sodium or potassium silicate solutions.

The following examples illustrate typicalwelding rod coating compositions including the novel compounds of my invention:

Example 1 Percent Wood flour 30 Ferromanganes 10 FeO- /2CaO-1 SiOz 45 Sodium silicate 15 This mixture may be applied as a coating to cluding my slagging and stabilizing compound constitute a novel product of my invention.

Welding rods with the composition of my invention are used in welding p in the same way as those hitherto known to the art.

I claim:

1. A composition for use in association with welding rods comprising a system of the formula FeO-xMeO-IISIO:

where a: and 11 represent the number of mols pres- .ent, and. where Me represents calcium orbarium, the compound having a melting point not substantially higher than 1300 C.

2. A composition for use in association with welding rods comprising a system of the formula where a: and 1; represent the number of mols present, the compound having a melting point not substantially higher than 1300' C. 3. A composition for coating welding rods com prising FeO-xMeOySiO:

where Me represents calcium or bariinn' and wherezisnomorethanabout 1 andwisbetween about V and 1%.

4. A composition for coating welding rods coma-- prising FeOotCaOilSiO:

where Me represents calcium or barium and where a: is no more than about 1 andw is between about 1 and 1%.

6. A composition for coating welding rods com- P moan-1.94

vFeo-motto-1115105 where a: is no more than about 1 and 1 is between about 1 and 1 /2.

7. A composition for coating welding rods com-- prising FCC-11380118102 where a: about andy is about 1 8. A composition for coating welding rods comprising I FeO-mCaO-ySlOz where a: is about M and y is about 9. A composition for coating welding rods com prising compounds of the formula where Me represents calcium or barium and a: and 11 represent the number of mols present, the compounds being of substantially uniform compo- .sition, being substantially free from deleterious impurities, and having a melting point not substantially higher than 1300 C.

10. As an article of manufacture a welding rod coated with a composition comprising FeO-mMeOySlOa where Me represents calcium or barium and .1:

and 11 represent the number of mols present, the

compound having a melting point not substantially higher than1300 C.

11. A welding rod-which has associated therewith a composition comprising:

FeO-zMeO-ySiOz FeO-azCaO-ySiOz wherein :c. is no more than about 1 and 11 is between about 1 and 1%.

PA UL C. LEMZMLERMAN. 

